1. Field of the Invention
The present invention relates to prepaid support for a mobile user of a telecommunications network.
2. Description of the Related Art
CDMA2000, also known as IMT-CDMA Multi-Carrier or IS-95, is a Code-Division Multiple Access (CDMA) version of the IMT-2000 standard developed by the International Telecommunication Union (ITU). The CDMA2000 standard is a third-generation (3-G) mobile wireless technology allowing mobile users to access IP-based high-speed voice and data traffic over the CDMA-based cellular network. CDMA2000 can support mobile data communications at speeds ranging from 144 Kbps to 2 Mbps.
Reference is now made to FIG. 1 (Prior Art) that shows a high-level block diagram of a CDMA2000 cellular telecommunications network 100. In the CDMA2000 wireless IP network 100, prepaid service allows an end-user 101 to purchase packet data service in advance based on volume or time. The prepaid account status is stored on a Prepaid server (PPS) 102 that is located in the end-user's home network 104 and accessed via a Home Authorization, Authentication & Accounting (HAAA) server 106. A Prepaid Client 108 residing in a Home Agent 109 communicates with the PPS 102 via the HAAA server 106. The function of the Prepaid Client 108 is to perform on-line accounting of the Mobile IP session (i.e.: to allow the Mobile IP traffic according to the granted volume or duration, and to block the Mobile IP traffic if not granted). To provide service to roaming prepaid end-users, a visited PDSN 110 also needs to support a Prepaid Client 111 for performing on-line accounting of the IP session (i.e.: to allow the IP traffic according to the granted volume or duration, and to block the IP traffic if not granted). Accounting messages from the visited PDSN 110 are possibly sent to the Home AAA server 106 via visited AAA server 116, which serves as proxy. The HAAA 106 and the Prepaid server 102 can be collocated in which case the collocated functionality may be denoted HAA/PPS, or could be separate entities. From the PDSN 110 or the HA 108 perspective, the HAAA 106 and the PPS 102 are indistinguishable. The interface between the HAAA 106 and the Prepaid server 102 is outside the scope of the present invention.
When a prepaid user 101 performs Simple IP with authentication or Mobile IP access, the PDSN 110 sends a RADIUS (Remote Authentication Dial In User Service) Access-Request message (not shown) to the HAAA/PPS server for Authentication and Authorization. The PDSN 110 also informs the HAAA/PPS of its own capabilities in supporting Prepaid with on-line accounting, so that proper actions for the support of the prepaid service are taken by the Home AAA 106 or Prepaid server 102 based on those capabilities. In current implementations, the actions taken by the HAAA/PPS server are limited to either participating to the prepaid support provided by the PDSN 110, or denying prepaid support when the PDSN 110 is detected as not supporting the prepaid feature. Usually, the denial of prepaid support implies that the end-user's access is immediately rejected, therefore barring the end-subscriber from using any functions of the wireless IP network.
In summary, in current implementations, a prepaid access request from a prepaid subscriber is rejected as soon as the PDSN is detected as not supporting the prepaid feature. However, this situation results in lost traffic and by consequence in lost revenues for the network operator. There is therefore a need for a solution wherein prepaid sessions can be supported even in absence of PDSN prepaid support. The present invention provides such a solution.